My bench power supply just started acting weird during a board test

I was checking a laptop motherboard from a 2019 Dell, trying to find a short on the 3.3 volt line. I had my Rigol DP832 set to 3.3V and a 3 amp limit, like I always do. Out of nowhere, the voltage reading on the display started jumping around, like from 3.3 to 4.1 and back, even though the output felt steady at the probes. I mean, it was fine last week. I shut it off, opened it up, and blew out all the dust, but the problem came back after ten minutes. I'm thinking it might be a bad capacitor or a loose connection on the display board itself. Has anyone else had a Rigol supply do this? I'm not sure if I should try to fix it or just start looking for a new one.

3 comments

3 Comments

alex_johnson26d ago

Yeah, that sounds exactly like the ribbon cable issue. Betty's right, it's a super common failure point on these. I'd reseat both ends of that flat cable before you do anything else, it's a five minute fix. If that doesn't work, then maybe start looking at caps.

ramirez.betty27d ago

My Rigol did the same thing last month. The display board ribbon cable was loose inside. Pushed it back in and it's been fine since.

wilson.kelly24d ago

Did you check the little voltage sense wires too? Mine did the same thing and one of those had worked itself loose at the banana jack.